Blender crashes when enabling "true" displacement
This doesn't explain the crash but does offer a way to work around the issue.

I noticed that your OSL script is generating a Color to pass into the Displacement. The Displacement is a Scalar value (at the moment - I believe the future incarnation of True Displacement will offer a Vector - much more versatile) and so there is no benefit in generating your displacement as a Color - it will be converted to and interpreted as a scalar value anyway.

By amending the OSL code to generate a float rather than Color, Blender no longer seems to crash :





Further to this, it appears to be specific to the type of noise used. For example, changing using 'usimplex' instead of 'uperlin' does not trigger the issue - also fine for 'cell', 'simplex', 'perlin' (without the 'u'), 'gabor', etc. all seem to work fine but for some reason 'uperlin' causes the crash - but only if you actually try to 'use' one of the elements of the color (eg, color c = noise('uperlin’, P*Scale, Time); Displacement = c[0]; causes it to crash).